1. Field of the Invention
The present invention relates to a ball joint highly improved in precision, endurance and functional smoothness, and an assembling method thereof.
2. Prior art
Conventionally, in an independent suspension of vehicle, since there is a necessity of changing of steering angle of wheels without deteriorating its function, a ball joint is used at a joint portion between a knuckle arm and a connecting rod, as shown in FIG. 13,. the ball joint 1 comprises a stud 2 at one end of which a spherical body 2a is provided and a race 3, and the spherical body 2a is held by the race 3. The spherical body 2a is held due to a guide face 3a of the race 3 in such a manner as it is not slipped out from the race 3 and a swing of a spherical body 2a in so-called six axial directions (X-axis, Y-axis, Z-axis, xcex8x-axis, xcex8y-axis and xcex8z-axis) is allowed. For reference, between the spherical body 2a and the guide face 3a grease is supplied to guarantee its slidability.
In a conventional ball joint 1, since it is free in its rotation direction and superior in its load resistance and endurance, it has widely used in conventional vehicle elements of vehicle suspension. However, since a displacement between the spherical body 2a and the guide face 3a is secured by being slid, there is a deterioration in its functional precision and operational smoothness, and since the swing angle is small, the applicable field has not spread to the table supporting mechanism of a multi-shaft machinery center.
Accordingly, to the above table supporting mechanism which requires a micron unit of precision and a large swing angle, with a combination of plural number of a single freedom of joint a rotary operation of three or six shafts has been realized. However, the joint of such combination which is of a multi-freedom of joint has caused to be of complicated in structure and increased in weight, in addition, so that, in order to position the shaft precisely, it is necessary to consider to control the operation in consideration of the deviation of the center of the shaft.
The present invention has been made in the light of the above problem, and the purpose thereof is to provide a bearing mechanism which is not limited in the rotational direction, superior in load resistance and endurance, large in swing angle and of a high level of precision of operation and functional smoothness.
In order to solve the above problem, a free spherical ball bearing according to a first aspect of the present invention, between a spherical inner race and an outer race prepared in a unit with the inner race while surrounding a part thereof through a resiliently changeable retainer balls are supported.
In this invention, since, by the rotation of the balls, a deflection between the spherical inner race and the outer race formed in a unitary manner with the inner race surrounding a portion of the inner race, is secured, it is superior in an operational smoothness. Further, since the outer race is a unitary member, it becomes possible to obtain easily a desired precision of part to attain a high operational precision. In addition, depending on the area by being surrounded with the inner race, the mutual swing angle between the inner race and the outer race can be determined.
And that, since the retainer is possible to be resiliently deformed, at the time of assembling the outer race, the inner race and the balls, the interference of each member is absorbed by the deformation of the retainer.
Further, according to a second aspect of the free spherical ball bearing of the present invention, the retainer is configured shell-like and split at least in one portion thereof. Accordingly, the shell is resiliently deformed positively at its split portion, and absorbs any interference between members assembled.
Further according to a third aspect of the free spherical ball bearing of the present invention, the retainer is formed with a combination of at least two members. According to this structure, by displacing the position relation between two members within the area in which a resilient deformation is possible, the interference between members is absorbed when the outer race, the inner race and the balls are assembled.
Further, according to a fourth aspect of the free spherical ball bearing of the present invention, the retainer is formed with a combination of two symmetrical members. Therefore, there is no need of preparing plural members to form a retainer, thereby a simplification of the structural parts is intended.
Further, according to a fifth aspect of the free spherical ball bearing of the present invention, it is formed with members different in size. In this case, it can make the members deformed in configuration in such a manner as it is configured effectively to generate the deformation of the retainer in order to absorb an interference, between the outer race, the inner race and the balls at the time of assembling.
According to a sixth aspect of the free spherical ball bearing of the present invention, a dividing line of the retainer is provided in priority of the arrangement of the balls. Said balls are requested to reduce a rotary resistance of the bearing and increase the endurance being arranged in such a manner as the load between the outer race and the inner race is dispersed. For that purpose, the above dividing line is provided without braking such arrangement to avoid it from being deteriorated in such function.
Further, according to a seventh aspect of the free spherical ball bearing of the present invention, the retainer comprises a ball receptor portion to accept the balls by being resiliently deformed and a grease receptor to dispose the grease. By this structure, the balls can be coupled with the receptor from the outside of the retainer. In addition by disposing the grease in the grease receptor, the lubrication of the outer race, the inner race and the balls is secured.
Further, according to an eighth aspect of the free spherical ball bearing of the present invention, on the end of the retainer a seal is provided to seal the grease. Thereby, the grease is secured to be sealed.
According to a ninth aspect of the free spherical ball bearing according to the present invention, to the inner race a stud is secured. Accordingly, this stud secures a six axial rotational movement due to a relative displacement of the inner race to the outer race.
Further, according to a tenth aspect of the free spherical ball bearing of the present invention, a shaft is supported slidably due to the inner race. Accordingly, the shaft is adapted to be secured with the six axial rotation movement by the relative displacement of the inner race to the outer race, and given a frequent appearance operation to the inner race.
In addition, according to eleventh aspect of the free spherical ball bearing, to at least the surfaces of the inner race, the outer race and the balls, a hardening treatment is applied to improve the load resistance and the endurance.
In order to solve the above problem an assembling method according to a twelfth aspect of the free spherical ball bearing is characterized in that, between the spherical inner race and the outer race which surrounds a part of the inner race in a unit, balls are supported by the shell-like retainer which is divided at least at one portion and deformable resiliently, the inner race is covered with retainer and after inserting in the outer race, the balls are coupled with the retainer.
According to this invention, at the time of inserting the inner race and the retainer into the outer race, by deforming the retainer resiliently by the amount of the gap between the inner race to expect to absorb the interference between the outer race and the retainer. Since the retainer is divided at least at one portion, at said dividing line a positive resilient deformation is generated and from the outside of the retainer the balls are coupled with. The balls coupled with the retainer are maintained due to a resilient restoring force of the retainer.
Further, according to a thirteenth aspect of the assembling method of the free spherical ball bearing, the outer diameter of the retainer is made to be shortened and inserted into the outer race. In accordance with this invention, the outer diameter of the retainer is made to be reduced resiliently and at the time of inserting of the inner race and the retainer into the outer race the interference between the outer race and the retainer is absorbed. And, after being inserted, the retainer is restored in the original configuration due to the restoring force of itself.
According to a fourteenth aspect of the assembling method of the free spherical ball bearing of the present invention, after covering the inner race with the retainer, the retainer is deflected along the dividing line and inserted in the outer race. In accordance with this invention, by deflecting the retainer along its dividing line, positively a deformation is made to be generated with the retainer. And, the interference of the outer race and the inner race at the time of inserting of the inner race and the retainer into the outer race is absorbed. After inserting, the retainer restores in its original configuration due to its restoring force.
According to a fifteenth aspect of the assembling method of the free spherical ball bearing of the present invention, the retainer is covered with the divided retainer portion, and after being inserted into the outer race, and other portion divided is inserted in the gap between the inner race and the outer race. In accordance with this invention, by inserting one portion of the retainer divided in a plurality into the outer race with the inner race, the interference at the time of inserting process is diminished, and after that, by inserting other part of the retainer into the gap between the inner race and the outer race, the shell-like retainer is finished.